Which statement best describes the process of osmosis regarding water and ion balance across a cell membrane?

• A. Water moves from an area of lower solute concentration to an area of higher solute concentration through a semipermeable membrane.
• B. Osmosis involves the movement of solute molecules from an area of higher concentration to an area of lower concentration.
• C. Ions move from an area of higher water concentration to an area of lower water concentration through a semipermeable membrane.
• D. Water and ions move together from an area of higher solute concentration to an area of lower solute concentration.

Answer: (A)

Verified step by step guidance

1. Understand that osmosis is the movement of water molecules across a semipermeable membrane, which allows water to pass but restricts many solutes.
2. Recognize that water moves to balance solute concentrations on both sides of the membrane, moving from the side with lower solute concentration (higher water concentration) to the side with higher solute concentration (lower water concentration).
3. Note that solute molecules themselves do not move during osmosis; instead, water moves to dilute the higher solute concentration side.
4. Recall that ions typically require specific channels or transporters to cross membranes and do not freely move with water during osmosis.
5. Conclude that the best description of osmosis is: water moves from an area of lower solute concentration to an area of higher solute concentration through a semipermeable membrane.